Interlock defeater for trip unit



Feb. 9, 1960 w. H. EDMUNDS INTERLOCK DEFEATER FOR TRIP UNIT 3 Sheets-Sheet 2 Filed Nov. 23, 1956 IN VEN TOR. Max/4M flifdzo [mm/4 0.1

Feb. 9, 1960 Filed Nov. 23, 1956 W. H. EDMUNDS INTERLOCK DEFEATER FOR TRIP UNIT 3 SheetsSheet 3 United States Patent INTERLOCK DEFEATER FOR TRIP UNIT Wiliam Harold Edmunds, Havertown, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application November 23, 1956, Serial No. 623,884 12 Claims. (Cl. 200-116) My invention relates to a circuit interrupter of the type shown in my copending applications Serial No. 461,378, filed October 11, 1954, and Serial No. 622,042, filed November 14, 1956, where a current limiting device and series connected circuit breaker are electrically coordinated and mechanically interlocked and more specifically relates to a means for defeating the mechanical interlock.

The combination of a series connected circuit breaker and current limiting device has been set forth in my copending application Serial No. 461,378 above noted, and a construction wherein the current limiters and circuit breaker are placed in individual housings which are removably connected to one another is set forth in copending application Serial No. 472,969, filed December 3, 1954, now Patent No. 2,888,535, and Serial No. 622,042, above noted. 1

In essence, this combination allows the use of a circuit breaker having a lower interrupting rating than the short circuit capacity of the protected system wherein the circuit breaker is provided with thermal trip units for opening a circuit after prolonged overloads and an instantaneous trip unit for opening the circuit under relatively low fault values. When a strong fault appears or a fault which exceeds a predetermined cross-over point, the series connected current limiting fuse operates to interrupt the circuit rather than the circuit breaker which may not be large enough to interrupt this fault value.

As well as being electrically coordinated as seen above, the two devices are also mechanically coordinated in that operation of the current limiting fuse of any phase (when operating in a multiphase system) will automatically trip the circuit breaker contacts of each phase.

When a standard circuit breaker is adapted for use in conjunction with a current limiter as set forth above, it is necessary that the trip unit be rno'dified to provide the mechanical interlock with the current limiters. Thus, two different types of trip units are required, the one to be used depending on the type of application of the circuit breaker.

The principle of my invention is to provide a single trip unit which has the mechanical interlock so constructed as to be defeatable.

Hence, only a single type of trip unit need be manufactured and stocked, this trip unit being normally operable for mechanical cooperation with a current limiting device. When, however, the circuit breaker is to be used by itself, the interlock mechanism of the trip unit is rendered inoperative.

In a preferred embodiment of my invention, the trip unit has an interlock rod which has a portion thereof positioned adjacent the space where a current limiter is to be mounted. When the current limiter housing is then disconnected or if one of the current limiting devices is operated, the interlock rod will be moved to cause operation of the circuit breaker tripper bar to open the circuit breaker contacts.

In accordance with my invention, the interlock rod is constructed to be made selectively inoperable to prevent ice interlock operation. By way of example, the interlock rod may have a hole therein for receiving a pin which will maintain the interlock rod away from the interlock position. Similarly, an adjustable collar positioned along the interlock rod may be positionable so that operation of the interlock will not connect the rod to the tripper bar.

Clearly, in either case, after defeat of the interlock mechanism the same trip unit may be used for standard circuit breaker operation.

Accordingly, a primary object of my invention is to provide a novel defeater for the trip unit interlock of a coordinated circuit breaker and current interrupting device.

Another object of my invention is to provide a single trip unit which could be used for either a standard circuitbreaker or for a combined circuit breaker and current limiter combination.

Still another object of my invention is to provide a trip unit having a defeatable interlock rod.

Another object of my invention is to defeat the trip unit of the'above described device and to replace the fuses by current connecting means which short circuit the fuse terminals and serve as a positive perceivable disconnect means for the circuit breaker.

These and other objects of my invention will become apparent from the following description when taken in conjunction with the drawings, in which:

Figure 1 is a perspective view showing a circuit interrupting device comprising a circuit breaker contained within a first housing and a current limiting device contained within a second and removable housing.

Figure 2 is an exploded perspective view of the current limiting device and housing of Figure 1.

Figure 3 shows a cross-sectional view through one phase of Figure 1. 9

Figure 4 shows a fragmentary top view of Figure 3 where a pin is inserted in the interlock rod to defeat the interlock.

Figure 5 is a second embodiment of my novel invention.

Referring first to Figure 1, a circuit breaker housing 20 has an extension 21 connectible to one end thereof by means of screws such as screws 24 and 25 which pass through openings 28 and 29 respectively which fasten into cooperating openings in circuit breaker housing 20.

If desired, extension 21 could be an integral part of the circuit breaker base asis shown in my above mentioned copending application Serial No. 622,042.

Contained within circuit breaker housing 20 is an operating mechanism of any desired type such as that shown in my US. Patent No. 2,574,093 which is operable by operating handle 30 for operating a pair of contacts for each phase of the circuit breaker. Each of the pairs of contacts of each phase is then terminated on one side by disconnect contacts 31, 32 and a contact 33, which cannot be seen in Figure 1, respectively.

The extension 21 provides additional disconnect contacts 34, 35 and 36 which cooperate with contacts 31, 32 and 33 respectively for connecting a current limiting devicein series with each of the circuit breaker phases.

Each of disconnect contacts 31 through 36 are of the tulip clip type such as that described in copendingapplication Serial No. 536,586, filed September 26, 1955,, and assigned to the assigneeof the instant invention, which are constructe'dto receive a stud in electrical and.

mechanical engagement.

However, disconnect contacts 31" through 36 could be of any desired type.

Current limiting devices for cooperatingwith' each of the circuit breaker phases are housed within housing;

3 37. Figure 2 more specifically shows these current limiting devices as fuses 38, 39 and 40 which are provided with disconnect studs 4142, 43-44, and 45-46 respectively. As seen in Figure 1, fuse 40 is connected to its corresponding phase by connection of disconnects 41 and 42, and disconnects 36 and 33 respectively. In a similar manner, disconnects 43, 44 and 45, 46 of Figure 2 will cooperate with disconnects 35, 32 and 34, 31 respectively of Figure 1.

Fuses 38, 39 and 40 are maintained in housing 37 by retaining plate 47 which is fastened to housing 37 by screws 48 and 49 as seen in Figure 2 and described in co-pending application Serial No. 582,552 filed May 31, 1956, and the assembled'housing is connected to the circuit breaker housing by screws 50 and 51 which pass through apertures 52 and 53 respectively and into tapped openings 54 and 55 of extension 21 as seen in Figure 1.

As may seen in the above noted copending application Serial No. 472,969 each of fuses 38, 39 and 40 are provided with a striker pin such as striker pin 85 of fuse 40 which is ejected from the fuse upon operation thereof. The striker pins are positioned to pass through a cooperating aperture in its respective disconnect, such as aperture 56 of disconnect 42 which cooperates with striker pin 85.

An auxiliary tripper bar 57 is pivotally mounted within housing 37 as seen in Figures 1 and 2 and as best seen in Figure 2, tripper bar 57 has extensions 58, 59 and 60 thereon which are positioned to be engaged by the striker pins of fuses 38, 39 and 40 respectively upon operation thereof.

A further extension 61 is fastened to auxiliary tripper bar 57 which, as will be seen hereinafter, is biased into operative engagement with the tripper bar of the circuit breaker by biasing spring 61a.

Figure 3 shows a cross-sectional view of the assembled components of Figure 1 when taken through the phase including fuse 40.

As seen in Figure 3 which shows screw 24 fastened to circuit breaker housing 24), a tulip clip type contact 62 is electrically connected to contact 36 and is fastened within housing 21 in any desired manner. Clearly, a set of disconnects similar to disconnect 62 will be provided for each of disconnects 34 and 35.

The circuit breaker 20 is provided with a similar set of disconnects such as disconnect contact 63 wherein disconnects 62 and 63 cooperate for plug-in engagement with studs 64 and 65 respectively of mounting blocks 66 and 67 which may be fastened within a switch board. Clearly, each of the other phases will be provided with similar sets of disconnects for cooperating with corresponding mounting blocks.

As an alternative, Figure 3 shows that a straight terminal 68 could be brought out as seen in dotted lines where connection to the current interrupting device is made at lead connecting means 69.

The current path of the phase shown in Figure 3 includes stud 65, circuit breaker tulip clip 63, stationary contact 70, movable contact of contact arm 71, a pigtail (not shown) which connects contact arm 71 to conductor 72, heater 73, coil 74, conductor 75, tulip clip 33, stud 42, fuse 40, stud 41, tulip clip 36 and tulip clip 62, and stud 64.

Coil 74 has a pivotally mounted armature 76 and a plunger 77 associated therewith, these components comprising the magnetic trip unit. Heater 73 hasbimetal 78 and adjusting screw 79 associated therewith, these components comprising the thermal-trip unit.

A tripper bar 80 is then seen in Figure 3 as having member 81 fastened thereto which carries adjusting screw 79 in cooperating alignment with bimetal 78 and is itself aligned with plunger 77.

Member 81 has one endthereof protruding into slot 4 82 of trip rod 83 and is rotatable in a counterclockwise direction within slot 82.

The operating mechanism 84 has a latch member 85 connected thereto and constructed to be latched by tripper bar 80. When tripper bar is rotated in a counterclockwise direction, however, latch member will be unlatched to allow mechanism 84 to disengage the circuit breaker cooperating contacts of each phase since mechanism 84 is constructed to be common to each phase.

In the event of a prolonged overload, heater 73 will cause bimetal 78 to deflect into engagement with screw 79 to cause counterclockwise rotation of tripper bar 80 and tripping of the circuit breaker contacts.

Under fault conditions, coil 74 will create a strong magnetic field to cause armature 76 to drive plunger 77 into engagement with member 81, thus rotating bar 80 counterclockwise to effect instantaneous tripping of the circuit breaker contacts.

Figure 3 further shows the striker pin 85 of fuse 40 as being positioned in registry with aperture 56 in disconnect 42 and extension 60 of auxiliary tripper bar 57 (see Figure 2).

When fuse 40 is operated (on faults above a predetermined value), striker pin 85 is ejected into engagement with extension 60 to rotate auxiliary tripper bar 57 (Figure 2) clockwise against the biasing force of spring 61a. This rotation will then remove extension 61 from tip 85a of trip rod 83 and allow biasing spring 86 to drive trip rod 83 to the left and rotate tripper bar 80 counterclockwise for tripping the circuit breaker contacts.

Thus, upon operation of one of the current limiting fuses such as fuse 40, the circuit breaker contacts will be disengaged to prevent single phasing and to disconnect the circuit.

It is important to note that the same action would be obtained if the fuse housing 37 were disconnected from the circuit breaker housing 20. That is, extension 61 of tripper bar 57 would be removed from tip 85a of link 83 to allow subsequent rotation of tripper bar 80.

Hence, in this construction wherein the fuse housing 37 is connected at the end of circuit breaker housing 20, the circuit breaker cooperating contacts will be disengaged responsive either to operation of any of the fuses or to removal of the fuse housing.

In order to defeat the interlock between the current limiting devices within fuse housing 37 and the circuit breaker tripper bar 80, a hole 93 is provided which can receive a pin means to prevent motion of tripper bar 83 to the left and subsequent tripping of the circuit breaker contacts.

Figure 4 which is a top view of the portion of Figure 3 which shows hole 90 of interlock rod 83 further shows a pin 91 inserted in the hole and bearing against housing portion 92 to prevent the biasing spring 86 from moving interlock rod 83 even though the member 61 of Figure 3 is removed from tip 85 of interlock rod 83.

Thus, by providing the circuit breaker 2!) with the novel trip unit shown in Figure 3 the circuit breaker may operate in conjunction with current limiting devices (or normal fuse devices if desired) or, after defeating interlock rod 83, the circuit breaker could operate as a standard circuit breaker without replacing the trip unit.

Figure 5 shows a second embodiment of my novel invention wherein parts similar to those of Figures 1, 2 and 3 have been assigned like numerals. in Figure 5, an auxiliary tripper bar 93 is pivotally mounted in current limiting device housing 37 at pivot 94 and is biased in a counterclockwise direction by biasing spring 95. A portion of auxiliary tripper bar 93 protrudes into the trip unit housing to engage tip 96 of interlock rod 97.

Interlock rod 97 is supported by bracket 98 and has a collar-.99 adjustably positioned thereon andv connectible to rod.97 by the set screw 100.

A biasing means (not shown) is then operative to bias interlock rod 97 to the left, but this motion is overcome by the stronger biasing force of spring 95.

When, however, auxiliary tripper bar 93 is removed from tip 96 by operation of a current limiting fuse or by removal of the fuse housing 37, interlock rod 97 may move to the left under its own biasing means whereby collar 99 engages member 81 of tripper bar 30 to rotate tripper bar it counterclockwise and trip the circuit breaker as has been set forth in conjunction with Figure 3.

p In order to defeat the interlock of Figure 5 to allow [the circuit breaker to operate in its normal manner, the set screw 100 may be loosened and collar 99 fastened at a position toward the right of the figure where it will not engage member 81 after full travel of interlock rod 97 to the left. Clearly, this leftward motion of tripper bar 97 can be limited in any desired manner so that the interlock would be inoperative when the collar 99 is removed to an inoperable position.

If desired, my novel defeatable trip unit would conveniently allow the use of a standard circuit breaker in conjunction with either current limiting devices or with current connecting means which are connected across the current limiting device terminals, to short circuit the terminals.

Thus the trip unit interlock would be made operative when the circuit breaker is coordinated with current limiters and inoperative when current conductors short out the current limiting fuse terminals to operate as a positive perceivable disconnect means for the circuit breaker.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art. I prefer therefore to be limited not by the specific disclosure herein, but only by the appended claims.

I claim:

1. In a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from an engaged position to a disengaged position responsive to operation of said trip means, a trip unit for operating said trip means; said trip unit comprising overload and instantaneous trip mechanism operatively connectible to said trip means for operating said trip means responsive to an overload for a predetermined time and for faults below a predetermined magnitude respectively; said trip uni-t being further comprised of interlock means operatively connectible to said trip means and being movable to operate said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined electrical and mechanical conditions of fuse devices connected to said circuit breaker; and manually operable means to defeat said operative connection between said interlock means and Said trip means to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with fuse devices.

2. In a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from an engaged position to a disengaged position responsive to operation of said trip means, a trip unit for operating said trip means; said trip unit comprising interlock means operatively connectible to said trip means and being movable to operate said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined electrical and mechanical conditions of a current limiting device connected. to said circuit breaker; and manually operable 6 means to defeat said operative connection between said interlock means and said trip means to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with a current limiting device.

3. in a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from a first to a second position responsive to operation of said trip means, a trip unit for 0 crating said trip means; said trip unit comprising interlock means operatively connectible to said trip means and being movable to operate said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined conditions of a fuse device connected to said circuit breaker; and defeater means to defeat said operative connection between said interlock means and said trip means to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with a fuse device.

4. In a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from an engaged position to a disengaged position responsive to operation of said trip means, a trip unit for operating said trip means; said trip unit comprising overload and instantaneous trip mechanism operatively connectible to said trip means for operating said trip means responsive to an overload for a predetermined time and for faults below a predetermined magnitude respectively; said trip unit being further comprised of interlock means operatively connectible to said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined electrical and mechanical conditions of a fuse device connected to said circuit breaker; and manually operable means to defeat said operative connection between said interlock means and said trip means; said interlock means comprising a member for operatively connecting said trip means controlling said cooperable contacts to the tripper bar of said fuse device when said fuse device is connected thereto; said interlock member having an aperture therein for receiving a pin means; said pin means being positioned to defeat said operative connection between said interlock means and said trip means by preventing motion of said interlock member to operate said trip means to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with a fuse device.

5. In a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from an engaged position to a disengaged position responsive to operation of said trip means, a trip unit for operating said trip means; said trip unit comprising overload and instantaneous trip mechanism operatively connectible to said trip means for operating said trip means responsive to an overload for a predetermined time and for faults below a predetermined magnitude respectively; said trip unit being further comprised of interlock means operatively connectible to said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined electrical and mechanical conditions of a current limiting device connected to said circuit breaker; and manually operable means to defeat sad operative connection between said interlock means and said trip means; said interlock means comprising a member for operatively connecting said trip means controlling said cooperable contacts to the tripper bar of current limiting device when said current limiting device is connected thereto; said interlock member having a collar adjustably positioned thereon; said collar being operatively connectible to said trip means when said collar is in a first position and being unconnectible to said trip means when in a second and defeated position to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with current limiting devices.

6. In a circuit breaker having a pair of cooperable contacts and a trip means, said trip means being operatively connected to said cooperable contacts, said cooperable contacts being movable from a first to a second position responsive to operation of said trip means, a trip unit for operating said trip means; said trip unit comprising interlock means operatively connectible to said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined conditions of a current limiting device to said circuit breaker; and defeater means to defeat said operative connection between said interlock means and said trip means; said interlock means comprising a member for operatively connecting said trip means controlling said cooperable contacts to the tripper bar of said current limiting device when said current limiting device is connected thereto, said interlock member having a collar adjustably positioned thereon; said collar being operatively connectible to said trip means when said collar is in a first position and being unconnectible to said trip means when in a second and defeated position to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with current limiting devices.

7., In a multiphase circuit breaker having a pair of cooperable contacts for each phase and a trip means, said trip means being operatively connected to each of said pairs of cooperable contacts, each of said pairs of cooperable contacts being movable from an engaged position to a disengaged position responsive to operation of said trip means; a trip unit for operating said trip means; said trip unit comprising overload and instantaneous trip mechanism operatively connectible to said trip means for operating said trip means responsive to an overload for a predetermined time and for faults below a predetermined magnitude respectively; said trip unit being further comprised of an interlock means operatively connectible to said trip means and being movable to operate said trip means; said interlock means being constructed to operate said trip means through said operative connection responsive to predetermined electrical and mechanical conditions of a current limiting device connected to said circuit breaker; and manually operable means to defeat said operative connection between said interlock means and said trip means to allow said trip unit to function either in a normal circuit breaker or in a circuit breaker adapted to operate in cooperation with current limiting devices.

8. In a circuit breaker having a pair of cooperable contacts and disconnect means for connecting a current limiting device having auxiliary trip means in series with said disconnect contacts; said circuit breaker having a trip means operatively connected to said cooperable contacts, a trip unit for operating said trip means; said trip unit comprising thermal and magnetic tripping mechanism operatively connectible to said trip means; said trip unit being further comprised of an interlock means and being movable to operate said trip means; said interlock means being constructed to operatively connect said trip means and the auxiliary trip means of a current limiting device when said current limiting device is connected by said disconnect means, whereby said trip means is operated responsive to operation of said auxiliary trip means; and a defeating means; said defeating means heing constructed to defeat said operative connection between said auxiliary trip means and said trip means.

9. In a circuit breaker having a pair of cooperable contacts and disconnect means for connecting a .current limiting device having auxiliary trip means in series with said disconnect contacts; said circuit breaker having a trip means operatively connected to said cooperable contacts; a trip unit for operating said trip means; said trip unit comprising thermal and magnetic tripping mechanism operatively connectible to said trip means; said trip unit being further comprised of an interlock means; said interlock means being constructed to operatively connect said trip means and the auxiliary trip means of a current limiting device when said current limiting device is connected by said disconnect means, whereby said trip means is operated responsive to operation of said auxiliary trip means; and a defeating means; said defeating means being constructed to defeat said operative connection between said auxiliary trip means and said trip means; said interlock means including a member having an aperture therein for receiving a pin means which forms said defeater means; said pin means being positioned to prevent motion of said interlock member responsive to operation of said auxiliary trip means to thereby defeat said operative connection therebetween.

10. In a circuit breaker having a pair of cooperable contacts and disconnect means for connecting a current limiting device having auxiliary trip means in series with said disconnect contacts; said circuit breaker having a trip. means operatively connected to said cooperable contacts, a trip unit for operating said trip means; said trip unit comprising thermal and magnetic tripping mechanism operatively connectible to said trip means; said trip unit being further comprised of an interlock means; said interlock means being constructed to operatively connect said trip means and the auxiliary trip means of a current limiting device when said current limiting device is connected by said disconnect means, whereby said trip means is operated responsive to operation of said auxiliary trip means; and a defeating means; said defeating means being constructed to defeat said operative connection between said auxiliary trip means and said trip means; said interlock means including a member having a collar adjustably positioned therein; said collar being operatively connectible to said trip means when said collar is in a first position and being unconnectible to said trip means when in a second and defeated position.

11. In a circuit breaker trip unit comprising thermal and magnetic trip mechanism operatively connectible to a circuit breaker trip means, a slidably mounted interlock means; said interlock means being constructed and positioned to operatively connect an auxiliary trip means to said circuit breaker trip means; said interlock means being constructed to be manually defeatable whereby said trip unit is adaptable for operation with a standard circuit breaker with said interlock means defeated or with a circuit breaker coordinated with devices having auxiliary trip means when said interlock means is operative; said interlock means including a member having an aperture therein for receiving a pin means which forms said defeater means; said pin means being positioned to prevent motion of said interlock member responsive to operation of said auxiliary trip means to thereby defeat said operative connection therebetween.

12. In a circuit breaker trip unit comprising thermal and magnetic trip mechanism operatively connectible to a circuit breaker trip means; a slidably mounted interlock means; said interlock means being constructed and positioned to operatively connect an auxiliary trip means to said circuit breaker trip means; said interlock means being constructed to be manually defeatable whereby said trip unit is adaptable for operation with a standard circuit breaker with said interlock means defeated or with a circuit breaker coordinated with devices having 9 auxiliary trip means when said interlock means is operative; said interlock means including a member having a collar adjustably positioned thereon; said collar being operatively connectible to said trip means when said collar is in a first position and being unconnectible to said trip means When in a second and defeated position.

References Cited in the file of this patent UNITED STATES PATENTS 10 Wyman Oct. 13, Milano Oct. 2, Benjamin Feb. 5, Corbett Mar. 2, Linde May 27, Dannenberg Sept. 28, Parkhurst et al. May 16, Scott June 10, Dannenberg June 14, Spiro July 12, Edmunds Nov. 6, Kozacka May 28, 

